Colour-groups of the Hawaiian Wasps, etc. 699 



any species is, as a very rare variety, liable to 

 produce such a form, the band in such case being 

 often very faint and fine, only found on one seg- 

 ment, sometimes fragmentary, or represented only 

 on the ventral surface, where it is, of course, 

 invisible in life. 



12. Though the nigripennis group is probably of much 



later origin in the islands than the other, which it 

 is to be noted has produced within the islands 

 distinct genera (Nesodynerus, Pseudopterocheilus, 

 Ghelodynerus), yet it also is ancient; for it is 

 represented by a highly modified species 0. localis 

 in Kauai, and by a second distinct one on Oahu, 

 0. epipseustcs. In localis such important structures 

 are modified that much time would be required. 



13. Consequently the arrival of the ancestor of the 



nigripennis group may well have happened at a 

 time when the condition of the avifauna was very 

 different. 



14. The nigripennis group of Odynerus might possibly 



have become much more numerous in species had 

 not the islands been already occupied by a great 

 number of forms developed from the earlier im- 

 migration. We may compare the case of the bird 

 family Drepanididae, with that of the later-arriving 

 Meliphagidae. 



Importance of the Hawaiian fauna in the study 



of Evolution. 

 Nov. 4, 1911. 



I believe the Hawaiian islands are for the solving of 

 many most important problems, without any equal else- 

 where as at present known. The excessive complications 

 of great continental faunas or continental islands are 

 absent, yet the fauna is itself large enough to present 

 many of the same phenomena. I saw this many years 

 ago and referred to it in my paper on the " Vertebrata " 

 (under the Birds) in the " Fauna Hawaiiensis." 



Nov. 13, 1911. 



I cannot follow the de Vries people at all. Their 

 mutations and fluctuations are distinctions without any 

 particular difference to me. They know nothing about 

 the instability of the latter. For instance, suppose we 



